Abstract:
Disclosed are methods and apparatus for providing feature classification for inspection of a photolithographic mask. A design database for fabrication of a mask includes polygons that are each defined by a set of vertices. Any of the polygons that abut each other are grouped together. Any grouped polygons are healed so as to eliminate interior edges of each set of grouped polygons to obtain a polygon corresponding to a covering region of such set of grouped polygons. Geometric constraints that specify requirements for detecting a plurality of feature classes are provided and used for detecting a plurality of feature classes in the polygons of the design database. The detected features classes are used to detect defects in the mask.
Abstract:
Block-to-block reticle inspection includes acquiring a swath image of a portion of a reticle with a reticle inspection sub-system, identifying a first occurrence of a block in the swatch image and at least a second occurrence of the block in the swath image substantially similar to the first occurrence of the block and determining at least one of a location, one or more geometrical characteristics of the block and a spatial offset between the first occurrence of the block and the at least a second occurrence of the block.
Abstract:
Block-to-block reticle inspection includes acquiring a swath image of a portion of a reticle with a reticle inspection sub-system, identifying a first occurrence of a block in the swatch image and at least a second occurrence of the block in the swath image substantially similar to the first occurrence of the block and determining at least one of a location, one or more geometrical characteristics of the block and a spatial offset between the first occurrence of the block and the at least a second occurrence of the block.
Abstract:
Systems and methods for detecting defects on a reticle are provided. The embodiments include generating and/or using a data structure that includes pairs of predetermined segments of a reticle pattern and corresponding near-field data. The near-field data for the predetermined segments may be determined by regression based on actual image(s) of a reticle generated by a detector of a reticle inspection system. Inspecting a reticle may then include separately comparing two or more segments of a pattern included in an inspection area on the reticle to the predetermined segments and assigning near-field data to at least one of the segments based on the predetermined segment to which it is most similar. The assigned near-field data can then be used to simulate an image that would be formed for the reticle by the detector, which can be compared to an actual image generated by the detector for defect detection.
Abstract:
Disclosed are methods and apparatus for qualifying a photolithographic reticle. A reticle inspection tool is used to acquire images at different imaging configurations from each of the pattern areas of a calibration reticle. A reticle near field is recovered for each of the pattern areas of the calibration reticle based on the acquired images from each pattern area of the calibration reticle. Using the recovered reticle near field for the calibration reticle, a lithography model for simulating wafer images is generated based on the reticle near field. Images are then acquired at different imaging configurations from each of the pattern areas of a test reticle. A reticle near field for the test reticle is then recovered based on the acquired images from the test reticle. The generated model is applied to the reticle near field for the test reticle to simulate a plurality of test wafer images, and the simulated test wafer images are analyzed to determine whether the test reticle will likely result in an unstable or defective wafer.
Abstract:
Disclosed are methods and apparatus for facilitating an inspection of a sample using an inspection tool. An inspection tool is used to obtain an image or signal from an EUV reticle that specifies an intensity variation across the EUV reticle, and this intensity variation is converted to a CD variation that removes a flare correction CD variation so as to generate a critical dimension uniformity (CDU) map without the flare correction CD variation. This removed flare correction CD variation originates from design data for fabricating the EUV reticle, and such flare correction CD variation is generally designed to compensate for flare differences that are present across a field of view (FOV) of a photolithography tool during a photolithography process. The CDU map is stored in one or more memory devices and/or displayed on a display device, for example, of the inspection tool or a photolithography system.
Abstract:
An optical reticle inspection tool is used during a first inspection to obtain, for each set of one or more patch areas of the reticle, a reference average of multiple reference intensity values corresponding to light measured from sub-areas of each patch area. After using the reticle in photolithography processes, the optical reticle inspection tool is used during a second inspection to obtain, for each set of one or more patch areas, an average of multiple test intensity values corresponding to light measured from the sub-areas. The first and second inspections use the same tool setup recipe. A difference intensity map is generated, and such map comprises map values that each corresponds to a difference between each average of the test and reference intensity values for each set of one or more patches. The difference intensity map indicates whether the reticle has degraded over time more than a predefined level.
Abstract:
Disclosed are methods and apparatus for inspecting an extreme ultraviolet (EUV) reticle using an optical inspection tool. An inspection tool having a pupil filter positioned at an imaging pupil is used to obtain a test image or signal from an output beam that is reflected and scattered from a test portion of an EUV test reticle. The pupil filter is configured to provide phase contrast in the output beam. A reference image or signal is obtained for a reference reticle portion that is designed to be identical to the test reticle portion. The test and reference images or signals are compared and it is determined whether the test reticle portion has any candidate defects based on such comparison. For each of a plurality of test reticle portions of the reticle, the operations for using the inspection tool, obtaining a reference image or signal, comparing, and determining are repeated. A defect report is generated based on any candidate defects that have been determined to be present.
Abstract:
Disclosed are methods and apparatus for facilitating an inspection of a sample using an inspection tool. An inspection tool is used to obtain an image or signal from an EUV reticle that specifies an intensity variation across the EUV reticle, and this intensity variation is converted to a CD variation that removes a flare correction CD variation so as to generate a critical dimension uniformity (CDU) map without the flare correction CD variation. This removed flare correction CD variation originates from design data for fabricating the EUV reticle, and such flare correction CD variation is generally designed to compensate for flare differences that are present across a field of view (FOV) of a photolithography tool during a photolithography process. The CDU map is stored in one or more memory devices and/or displayed on a display device, for example, of the inspection tool or a photolithography system.
Abstract:
Disclosed are methods and apparatus for providing feature classification for inspection of a photolithographic mask. A design database for fabrication of a mask includes polygons that are each defined by a set of vertices. Any of the polygons that abut each other are grouped together. Any grouped polygons are healed so as to eliminate interior edges of each set of grouped polygons to obtain a polygon corresponding to a covering region of such set of grouped polygons. Geometric constraints that specify requirements for detecting a plurality of feature classes are provided and used for detecting a plurality of feature classes in the polygons of the design database. The detected features classes are used to detect defects in the mask.